Gestational diabetes mellitus (GDM) complicates approximately 7% of pregnancies in the U.S. However, the epidemics of obesity and diabetes, as well as revised GDM diagnostic criteria, are dramatically increasing the prevalence of GDM, as high as 18% of pregnancies according to some estimates. This increasing prevalence is noteworthy because of the concomitant risk for adverse sequelae, not only in the peripartum period, such as increased rates of caesarean section delivery and neonatal birth injury, but also subsequent to pregnancy, including increased risk for type 2 diabetes mellitus (T2DM) for both mother and offspring. Early identification of women at increased risk for GDM would provide the opportunity for the development of targeted GDM and T2DM risk prevention strategies. Our proposal capitalizes on our expertise in emerging technologies, as well as our existing study populations, to further characterize women at increased risk for developing GDM and T2DM. Our Specific Aim 1 will examine a cohort of women followed during pregnancy for the development of GDM. Our Specific Aims 2-4 will examine the cohort of women within the Diabetes Prevention Program (DPP) with a history of GDM for the development of T2DM while examining the effects of study intervention and race on the outcome.